Chicken Stew (Kozhi Ishtew)

6 shallots, thinly sliced

2 onions, cut into thick wedges

3 green chilies, slit

1 tablespoon sliced fresh ginger

8 curry leaves

3 (1-inch) cinnamon sticks

4 cardamom pods , lightly crushed

6 whole cloves

1/2 tablespoon all-purpose flour

1 (3-pound) chicken, cut into 16 pieces or 4 boneless chicken breasts, quartered

2 large potatoes, quartered

1/2 tablespoon vinegar

3 cups water

3 cups thin coconut milk

1 tablespoon salt

1/2 cup thick coconut milk

1 teaspoon crushed black peppercorns